1. Field of the Invention
The present invention relates to an image storage memory that is capable of memorizing images effectively (i.e., compressively), and more particularly to an image storage memory that is lossless (i.e., reversible) by an application of quantization technology.
2. Background
As a lossless compressible technology for images, the Run-Length coding method is well known. An example of Run-Length coding as a compressible technology follows:
The example image is a binary image (i.e., a monochrome, black-and-white image), which comprises pixels of 30 rows as longitudinal by 30 columns as traverse.
When each pixel (dot) line of the first line is represented as code `0` to be white and as code `1` to be black, the line may be represented as `00000100000001000000100000001(29 bits)`. In this case, five digits may be represented as code `0` in the beginning, and then one digit may be represented as code `1`. Subsequently, seven digits, one digit, six digits, one digit, seven digits, and one digit are represented as code `0`, code `1`, code `0`, code `1`, code `0`, and code `1`, respectively. Thus, this is a method for coding consecutive number and compressing an image by decreasing number's portion repeated by the same number.
However, the problem of the above prior art is that an intended image cannot be individually read and reproduced at every pixel (i.e., through random access). That is, the most important factor of this problem is that it varies according to the data and therefore it cannot be regularly memorized.
Unless such random access can be made, it takes a large time period to process specific pixel data from an image system such as, for example, a 3D computer graphic.
In the case where specific image data in texture space is rendered on a CRT by rotation and reduction, as shown in FIG. 10(B, C), it cannot reproduce this on the CRT in a raster order, as it is, because the CRT image data is scanned and memorized in a raster scanning order in the texture space.
This causes a requirement to represent a surface as a line in the texture space on CRT, and to be unable to reproduce the original figure as it was by reduction.
It requires a lot of time to scan the data in a raster scanning order in a texture space, and to fetch specific, randomly accessed information.